when a car has a transmission with overdrive: what is overdrive and when should it be used?
overdrive is an extra gear. Automatic only. It should be off, in normal driving but say your going over 40 mph. You should keep it on, it drops rpms, because its a higher gear. So you get better mileage, more speed
overdrive is a extra gear you have and it should be used most of the time to help save gas and it takes the strain off the motor and transmission. i use it most of the time unless i,am driving where there is lots of hills then i use reg. drive.
Well - overdrive is an extra gear, but it doesn't necessarily have to be 1:1 - its actually over-driven past 1:1 (hence the name). Quite a few Turbo Hydramatic transmission series have overdrives down into the 0.6:1 range. And technically, the 6 speed T56 manual transmission on my camaro has an Overdrive - its the 6th gear selection, which is really only usable after about 70 mph. Just because its selected by me doesn't mean its any less of an overdrive. Unless you have to, always run your automatic in the overdrive selection - what this does is shift the car down to that gas-saving overdrive gear when possible. The only time you don't want to use it is in situation where you will bog, or otherwise lose much-required power (such as in towing, where you could cause excessive engine/trans wear by overdriving while pulling a heavy load).
